Coupling heads for use in securing tow bars and the like on vehicle bumpers have been provided for many years. Such coupling heads are utilized to tighten and secure a chain which is attached adjacent an upper edge of a bumper to the lower edge of the bumper. The coupling heads have included a lower bumper engaging portion together with means for receiving a threaded shank which has attachment at an upper end thereof to the chain. The threaded shank is secured to the coupling head by an internally threaded nut which must be screwed, as by a wrench, tightly into engagement with the coupling head for drawing the chain tightly so as to maintain the assembly in fixed relation to the bumper. Accidents have been found to occur when such assemblies become disengaged from the vehicle bumper. The chief cause of such accidental disengagement loosening of the chain which results from the chain having become twisted between its connection to the upper edge of the bumper and the threaded shank. For example, twisting occurs most often as when the internally threaded nut engages a rough portion of the threaded shank causing twisting of the shank imparting a twist to that portion of the chain between the shank and its connection to the upper edge of the bumper. During towing on the highway, the effects of a bump on the road may result in a momentary release of the tension on the twisted portion on the chain permitting untwisting of the chain with consequent loosening of the entire assembly upon the bumper.
Accordingly, it is an important object of this invention to provide a coupling head which will not depend upon the tightening of an internally threaded member upon the threaded shank for tightening the chain.
A further object of the invention is to provide a coupling head for securing a towing assembly which may be used without the necessity of a wrench for tightening the chain.
Still another important object of the invention is the provision of a coupling head which may be manually manipulated to draw the chain tight through a pivoting action of a mounting member which will be automatically locked in position retaining the fastening chain against any tendency to loosen in normal use in a vehicle towing operation.